Music recordings are composed mainly of two predominant components—the vocals or the singing voice and the instruments. Of these two components, the instruments are usually a combination of pitched and percussion instruments. Vocals separation or singing voice separation from polyphonic music (consisting of two or more simultaneous lines of independent melodies, in contrast to monophony—a musical texture with just one melody is a challenging problem, which attracted much attention recently owing to its multiple useful applications.
In music information retrieval (MIR) systems, vocals separation is useful in singer language identification, lyrics recognition and alignment, and melody extraction and transcription. In addition to its importance for MIR applications, separation of vocals could have many other benefits, such as in adjusting the vocal pitch, audio remixing, and creating a vocal or non-vocal equalizer for use in automatic karaoke applications.
However on examining traditional separation techniques employed, one can still hear harmonics of pitched instruments in the separated vocal tracks. The difficulty of the problem arises from the similarity between vocals and musical instruments since the spectra of both have harmonic structure. In addition, music instruments do not possess whiteness and stationarity properties of noise and thus cannot be separated by noise suppression techniques.
On experimenting with various traditional separation techniques and a variety of musical recordings, pitched instruments are still audible in the separated vocals. Harmonics of pitched instruments appear as horizontal ridges in a mixture spectrogram, and additional horizontal ridges representing harmonics of pitched instruments were available in all outcomes of traditional separation algorithms, in different proportions.
Accordingly, there exists a need to provide a methodology or processing technique to target pitched instruments harmonics and separate the same from separated vocal track regardless of the separation algorithm used.